JavaScript String Functions

var str = "this is a string";

console.log(str); // THIS WILL PRINT THE VARIABLE

var position = str.indexOf('is');
    console.log(position)

this function will give the first position of occurrence the given element.

IN THE GIVEN EXAMPLE ITS 2

THIS IS A STRING.

position = str.lastIndexOf('is');
    console.log(position)

this function will give the last position of occurrence the given element.

IN THE GIVEN EXAMPLE ITS 5

THIS IS A STRING.

Substring from a string

// var substr = str.slice(1,7);
    // var substr = str.substring(1,7);
    var substr1 = str.substr(1,3);
    console.log(substr1)

THESE ARE THE WAYS OF SLICING A STRING

SLICE CAN TAKE -VE VALUE AS INPUT WHILE SUB STRING CAN'T

FIRST VALUE IS INCLUDED LAST IS NOT

 // var replaced = str.replace('string', 'Harry');
    // console.log(str)
    // console.log(replaced)

THESE ARE THE REPLACE VARIABLES THESE ARE USED TO REPLACE ELEMENTS FROM STRING

IN THE GIVEN CASE THE THE OUTPUT WILL BE

FOR STR

THIS IS A STRING

FOR REPLACED

THIS IS A HARRY

  // console.log(str.toUpperCase()); 

// console.log(str.toLowerCase()); 

THIS WILL CONVERT TEXT TO UPPER AND LOWER CASE

// var newString = str.concat('New String')

SIMILAR AS OUR "+" OPERATOR

// var strWithWhitespaces = "   this contains        whitespaces   ";
    // console.log(strWithWhitespaces)
    // console.log(strWithWhitespaces.trim())

THE TRIM FUNCTION WILL TRIM ALL THE EXTRA WHITE SPACES IN THE BEGINNING AND END OF THE STRING BUT NOT IN THE MIDDLE

// var char2 = str.charAt(2);
    // var char2 = str.charCodeAt(2); // Not very important
    // console.log(char2)

WILL GIVE THE CHARACTER AT 2 AND IT'S CODE RESPECTIVELY

    console.log(str[3])

SAME AS ABOVE